It is important for operators working in a nuclear electricity generation plant or citizens living in a neighborhood of the nuclear electricity generation plant to reduce radiation exposure. Further, in a case where user wants to determine a position of radiation source in some place such as operation site, it is required that a radiation measurement apparatus that has a high portability or enables user to take it anywhere. Conventionally, radiation measurement technology disclosed in patent document 1 has known as an example of radiation measurement technology.
The radiation measurement technology disclosed in patent document 1 includes a radiation detector that is arranged in two-dimensional arrangement such as a matrix or the like and a collimator that arranges in front of the radiation detector and limits incoming direction of radiation, and visualizes radiation intensity as two dimensional distribution.